30 The equation = ndsinis used to calculate the wavelength of light in an experiment that uses a diffraction grating. Thelight from the diffraction grating is displayed on a screen.What do the symbols n and d represent?n dA number of slits in the grating distance between adjacent slits in the gratingB number of slits in the grating distance from grating to screenC order of intensity maximum distance between adjacent slits in the gratingD order of intensity maximum distance from grating to screen31 The diagram shows a metal block.abcI IThe block has sides of length a, b and c as shown, and its volume is V. Each charge carrier has acharge –q and the number density of the charge carriers in the metal is n. It takes each chargecarrier an average time of t to pass through the block.What is an expression for the current I ?A I = nqabc B I = nqVt C I = nqbct D I = nqaV

Light of wavelength 5.4  10 –7 m is incident normally on a diffraction grating.The separation between adjacent lines in the grating is 2.0  10 –6 m. The light that emerges fromthe grating falls on a semicircular screen, as shown in the view from above.diffraction gratingscreenVIEW FROM ABOVElight,wavelength 5.4  10 –7 mThe grating is at the centre of the semicircle, and the lines of the grating are vertical.How many bright dots are formed on the screen?A 3 B 4 C 6 D 7

A diffraction grating 2 cm wide is just able to resolve sodium D-lines (589 nm and589.6 nm) in second order. Find the number of rulings per mm.

Calculate the least width that a grating must have to resolve two components of thesodium D lines in the second order, the grating having 800 lines/cm. The wavelengthfor D1 and D2 lines of sodium are 5893 Å and 5896 Å respectively.

n part A of the experiment a pair of slits are illuminated with a laser and an interference pattern is observed. The slit spacing is d = 0.0001 m and the pattern is projected on to the wall a distance L= 2.49 m from the slits. From one dark spot 8 further dark spots are counted and the distance is measured to be Z = 0.109 m.Calculate the wavelength λ of the laser.Express answer in nm (1x10-9m) to the nearest whole number.

A diffraction grating, which has 4000 lines/cm is used at normal incidence. Calculatethe dispersive power of the grating in the third order spectrum in the wavelengthregion 5000Å.